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A275997 Numbers n whose deficiency is 64: 2n - sigma(n) = 64. 2
134, 284, 410, 632, 1292, 1628, 4064, 9752, 12224, 22712, 66992, 72944, 403988, 556544, 2161664, 2330528, 8517632, 13228352, 14563832, 15422912, 20732792, 89472632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Any term x = a(m) in this sequence can be used with any term y in A275996 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable.

The smallest amicable pair is (220, 284) = (A275996(2), a(2)) = (A063990(1), A063990(2)), where 284 - 220 = 64 is the abundance of 220 and the deficiency of 284.

The amicable pair (66928, 66992) = (A275996(7), a(11)) = (A063990(18), A063990(19)), where 66992 - 66928 = 64 is the deficiency of 66992 and the abundance of 66928.

LINKS

Table of n, a(n) for n=1..22.

EXAMPLE

a(1) = 134, since 2*134 - sigma(134) = 268 - 204 = 64.

MATHEMATICA

Select[Range[10^7], 2 # - DivisorSigma[1, #] == 64 &] (* Michael De Vlieger, Jan 10 2017 *)

PROG

(PARI) isok(n) = 2*n - sigma(n) == 64; \\ Michel Marcus, Dec 30 2016

CROSSREFS

Cf. A002025, A063990, A275996.

Sequence in context: A050963 A051387 A177348 * A007251 A219443 A230699

Adjacent sequences:  A275994 A275995 A275996 * A275998 A275999 A276000

KEYWORD

nonn,more

AUTHOR

Timothy L. Tiffin, Aug 16 2016

STATUS

approved

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Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)